Ventricular assist device cannula and ventricular assist device including the same

ABSTRACT

Provided is a ventricular assist device cannula, and more particularly, a ventricular assist device cannula with electrodes. An exemplary embodiment of the present invention provides a ventricular assist device cannula with electrodes, including: a connecting tube connecting an incision of a body tissue and a ventricular assist device so that blood can flow; and electrodes connected with the connecting tube and contacting the incision of the body tissue to transfer an electric signal to the body tissue. The ventricular assist device cannula with electrodes according to the exemplary embodiment of the present invention has effects as follows. First, a bio-signal of a patient wearing the ventricular assist device through the electrode attached to the conduit can be easily measured without a separate electrode implant and an electric stimulus can also be measured. Second, since the electric stimulus can be directly applied to a cardiac muscle, it is possible to improve stability and efficiency of an electric treatment such as a cardiac pacemaking, a ventricular defibrillation, and the like of the patient wearing the ventricular assist device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationSer. No. 13/286,631, filed on Nov. 1, 2011, which claims priority to andthe benefit of Korean Patent Application Nos. 10-2010-0112662,10-2010-0118306, 10-2010-0126867, 10-2010-0129026, and 10-2010-0129036filed in the Korean Intellectual Property Office on Nov. 12, 2010, Nov.25, 2010, Dec. 13, 2010, Dec. 16, 2010, and Dec. 16, 2010, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a ventricular assist device cannula anda ventricular assist device including the same.

(b) Description of the Related Art

A ventricular assist device (VAD) is generally used in the case where aninternal treatment has no effect on patients with heart failure or theheart failure is difficult to treat by open heart surgery. Theventricular assist device is operated so as to replace the function of aventricle before imprinting a heart or used in order to induce recoveryby reducing a load of the heart. The ventricular assist device generallyhas a structure which aspirates blood from an atrium or a ventricle byusing a cannula and then ejects the blood to the aorta.

The ventricular assist device is classified into an implantable typeventricular assist device and an extracoporeal type ventricular assistdevice according to an implanted region and into a left ventricularassist device (LVAD), a right ventricular assist device (RVAD), and abiventricular assist device (BiVAD) according to an assisted heartregion. The left ventricular assist device is mainly used. In addition,as another classifying method, the ventricular assist device may beclassified into a pneumatic type and an electric type according to adifference in methods of supplying a power source. The electric type issub-classified into an electrohydraulic type and an electromechanicaltype. In addition, the ventricular assist device may be classified intoa pulsatile type and a nonpulsatile type according to the existence ofpulsation when the blood is ejected according to a driving manner. Inaddition, an implantable biventricular assist device corresponds to amechanical heart, but is differentiated from a totally implantablemechanical heart in which blood circulation is performed by only themechanical heart after removing a natural heart.

Since a patient with a terminal heart disease using the ventricularassist device complexly shows problems such as the loss of a pumpingfunction of the heart, arrhythmia or ventricular fibrillation, andischemia, it is difficult to expect a significant improvement of thesurvival rate of the patient by using only the ventricular assistdevice.

For example, even though the patient with the terminal heart diseaseuses the ventricular assist device, the patient may die frominterruption of pulsation of the heart. Therefore, the survival rateneeds to be increased by using a defibrillator together. Further, it isalmost impossible to anticipate the pulsation timing of the heart of apatient with arrhythmia, a possibility that simultaneous pulsation whichmay impose a burden on the heart may occur is very high. Therefore, anartificial pacemaker capable of adjusting the pulsation timing of theheart needs to be used in conjunction with the ventricular assistdevice.

However, since a separate electrode for applying an electric stimulus tothe heart has to be transplanted in order to mount the defibrillator andthe artificial pacemaker, respectively, an additional operation and anin-vivo volume of the patient are required.

Meanwhile, when a separate external defibrillator is used, malfunctionand damage of the ventricular assist device may occur.

Meanwhile, the existing ventricular assist device can measure orestimate its own blood ejection amount, but since the existingventricular assist device cannot find a cardiac ejection amount of apatient and a total blood circulation amount, the existing ventricularassist device cannot perform optimal control according to aphysiological condition of the patient. When the ventricular assistdevice is used, an optimal amount of blood flow which the ventricularassist device will supply depending on the physiological condition ofthe patient is changed. It was difficult for the existing ventricularassist device to be equipped with an appropriate measurement device forexpecting physiological variation of the patient. If a blood flow supplyamount of the ventricular assist device is excessively large, arteriesor heart tissues around an inlet catheter may be narrowed or damaged andif the blood flow supply amount thereof is excessively small, an effectof assisting the heart is reduced. Further, when the ventricular assistdevice co-pulsates while the heart pulsates, a large load is applied toa heart muscle to damage the heart muscle. Therefore, a measurementtechnology which can be easily applied to the existing ventricularassist device simultaneously when measuring the cardiac output and acardiac ejection timing of the patient needs to be developed.

Meanwhile, the artificial pacemaker which normally pulsates the heart byusing an electric stimulus principle is primarily used for a patient whohas a pulse slower than a normal pulse or is under a risk of an expecteddeath. The artificial pacemaker is constituted by two parts of a pacegenerator and an electrode line. Between them, the pace generator is ametallic case including an electronic circuit controlling the electricstimulus and a battery and the electrode line serves to pulsate theheart by transferring electricity or send an electrical signal generatedfrom the heart to the pace generator. The artificial pacemaker isdivided into a temporary type and a permanent type. In the temporarytype, the power supply is provided outside the body and is used for apatient who requires pacemaking for several days. The permanent type isused for a patient who requires pacemaking for a long period of timewith a power supply thereof buried in the body. The pace generator isburied below a skin of an upper part of a chest and the electrode lineis inserted into the blood vessel to be connected to the inside of theheart. The electrode line may be fixed to the heart muscle. Theartificial pacemaker has a light weight of 20 to 30 g and also has asmall size. The life-span of the battery is continued for 7 to 13 years.Further, there is also provided a fully automatic type which has anoutput of the power supply and pulsation rate which can be controlledoutside the body and functions similar to a normal heart so as to allowthe patient to act similarly to a normal person.

Actually, it is almost impossible to anticipate a timing of the heartbeat of the heart of the patent with arrhythmia. Accordingly, when onlythe ventricular assist device is used, a possibility that simultaneouspulsation which may impose the large burden on the heart will occur isvery high.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide aventricular assist device cannula with electrodes having advantages oftransferring an electric stimulus to a heart and a blood vessel by adefibrillator and an artificial pacemaker, and the like so as to easilyuse devices such as the defibrillator, the artificial pacemaker, and thelike together with the ventricular assist device.

Further, the present invention has been made in an effort to provide aventricular assist device cannula with electrodes having anotheradvantage of increasing patient's survival rate and minimizingmalfunction and damaging causes of the device by developing a fusiondevice for minimizing an influence on each other while the ventricularassist device and the defibrillator operate simultaneously.

In addition, the present invention has been made in an effort to providea ventricular assist device having another advantage of easily measuringa cardiac output and an output timing by installing electrodes in acannula used in the ventricular assist device and measuring impedancebetween a heart and aorta.

Moreover, the present invention has been made in an effort to provide aventricular assist device including an artificial pacemaker havingadvantages of preventing the ventricular assist device from beingco-pulsated with the heart by controlling a timing and frequency of aheart beat using the artificial pacemaker.

An exemplary embodiment of the present invention provides a ventricularassist device cannula with electrodes, including: a connecting tubeconnecting an incision of a body tissue and a ventricular assist deviceso that blood can flow; and electrodes connected with the connectingtube and contacting the incision of the body tissue to transfer anelectric signal to the body tissue.

The electrode may be a conductive sheet attached to the surface of theconnecting tube.

The electrode may be a hollow electrode which has a hollow space intowhich the connecting tube is inserted at the inside thereof and iscontacted to the incision of the body tissue at the outside thereof. Areceiving groove receiving the incision of the body tissue may be formedat an outer circumference of the hollow electrode.

The electrode may be a connector electrode which has hollow space wherethe blood can flow at the inside thereof and includes a body partclosely contacted to the incision of the body tissue and inserted intothe body tissue and a fixing part extending from the body part andinserted and fixed to the connecting tube at the outside thereof. Areceiving groove receiving the incision of the body tissue may be formedat an outer circumference of the body part.

The electrode may have a hollow space where the blood can flow at theinside thereof and includes a body part closely contacted to theincision of the body tissue and fixing parts extending from the bodypart to the upstream and the downstream, respectively, at the outsidethereof, and the connecting tube may include a first connecting tubehaving one end connected to the fixing part and the other end insertedinto the body tissue and a second connecting tube having one endconnected to the fixing part and the other end connected to theventricular assist device. A receiving groove receiving the incision ofthe body tissue may be formed at an outer circumference of the bodypart.

Another exemplary embodiment of the present invention provides aventricular assist device including a defibrillator in the ventricularassist device including a blood pump pumping the blood, the deviceincluding: at least a pair of conduits including a connecting tubeconnecting an incision of a body tissue and the blood pump so that theblood can flow and electrodes connected with the connecting tube andcontacting the incision of the body tissue to transfer an electricsignal to the body tissue; a detecting device detecting an abnormalityof heart beat or not; a defibrillator applying an electric stimulus tothe heart by applying a defibrillation pulse to the electrode; and acontrol device receiving a signal from the detecting device to controlthe blood pump and the defibrillator.

The detecting device may include a pressure sensor measuring an inletpressure of the conduit.

The detecting device may include an impedance measuring device measuringimpedance between the electrodes.

The control device may operate a protection mode blocking a power supplyand input and output signals of the ventricular assist device whendefibrillation energy for applying a defibrillation pulse is charged inthe defibrillator. The control device may include an external alarmdevice sounding the alarm when ventricular fibrillation and a cardiacarrest are detected through the detecting device.

Yet another exemplary embodiment of the present invention provides aventricular assist device including an impedance measuring device in theventricular assist device including a first conduit and a second conduitwhere blood flows and a blood pump pumping the blood, the deviceincluding: a first conduit including a connecting tube connecting anincision of a first body tissue and the blood pump so that the blood canflow and a first electrode connected with the connecting tube andcontacting the incision of the first body tissue to transfer an electricsignal to the first body tissue; a second electrode spaced apart fromthe first electrode with the first body tissue interposed therebetweenso as to measure impedance due to the blood flow in the first bodytissue connected to the first conduit; an impedance measuring devicemeasuring impedance between the first electrode and the secondelectrode; and a control device receiving a signal from the impedancemeasuring device to control operation of the blood pump.

Still another exemplary embodiment of the present invention provides aventricular assist device including an artificial pacemaker in theventricular assist device including a blood pump pumping the blood, thedevice including: at least a pair of conduits including a connectingtube connecting an incision of a body tissue and the blood pump so thatthe blood can flow and electrodes connected with the connecting tube andcontacting the incision of the body tissue to transfer an electricsignal to the body tissue; a detecting device detecting a cardiac signalof a patient; an artificial pacemaker applying an electric stimulus tothe heart through the electrode; and a control device receiving a signalfrom the detecting device to control the blood pump and the artificialpacemaker.

The detecting device may include a pressure sensor measuring an inletpressure of the conduit.

The detecting device may include an impedance measuring device measuringimpedance between the electrodes.

The control device may compare heart rate with pulsation rate of theblood pump, and if the heart rate is smaller than the pulsation rate ofthe blood pump, the heart rate may be equal to the pulsation rate of theblood pump by controlling the artificial pacemaker, and if the heartrate is X to X+1 times (X is a natural number of 1 or more) larger thanthe pulsation rate of the blood pump, the heart rate may be equal to beX+1 times of the pulsation rate of the blood pump by controlling theartificial pacemaker.

The control device may control a blood pump output using a cardiacoutput measured in the detecting device as a parameter.

According to the exemplary embodiments of the present invention, theventricular assist device cannula with electrodes has effects asfollows.

First, a bio-signal of a patient wearing the ventricular assist devicethrough the electrode attached to the conduit can be easily measuredwithout a separate electrode implant and an electric stimulus can alsobe measured.

Second, since the electric stimulus can be directly applied to a cardiacmuscle, it is possible to improve stability and efficiency of anelectric treatment such as a cardiac pacemaking, a ventriculardefibrillation, and the like of the patient wearing the ventricularassist device.

According to the exemplary embodiments of the present invention, it ispossible to provide an efficient defibrillation method for restoring aheart function against fatal arrhythmia which may occur during a use ofthe ventricular assist device. Further, it is possible to minimizepossibilities of malfunction and damage of the ventricular assist devicewhich may occur by an operation of a separate defibrillator. Inaddition, a fast and efficient defibrillation can be performed even by asmall electric stimulus as compared with a general defibrillation methodby applying a direct electric stimulus to a Purkinje fiber of a heartmuscle.

According to the exemplary embodiments of the present invention, theventricular assist device including a measuring device of a cardiacoutput and a cardiac output timing has effects as follows.

First, since a blood flow of a patient and an output timing of blood areexpected by measuring impedance, it is possible to perform an optimalcontrol suitable for a physiological condition of the patient. That is,when the circulation of the entire blood flow is reduced, the blood flowspeed of the ventricular assist device decreases, such that it ispossible to prevent the blood vessel from being contracted or damageddue to an excessive inflow of the blood flow and minimize a load appliedto the heart of the patient due to a simultaneous beat by preventing theblood ejection of the ventricular assist device in the heart ejection.

Second, it is possible to verify an open or close of valves by measuringimpedance of a current path to be connected to a blood vessel, an aorticvalve, and a heart of the patient.

Third, it is possible to measure and monitor a heart beat state and amotion state of valves of the patient for a long time without a separateexpert and detect a dangerous factor in real time.

According to the exemplary embodiments of the present invention, sincethe ventricular assist device can control a timing of the heart beat byusing an artificial pacemaker, it is possible to prevent fatalarrhythmia and simultaneous pulsation generated during a use of theventricular assist device. Further, a fast and efficient cardiacpacemaking can be performed even by a small electric stimulus ascompared with a general defibrillation method by applying a directelectric stimulus to a Purkinje fiber of a heart muscle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a ventricular assist device cannula withelectrodes according to a first exemplary embodiment of the presentinvention.

FIG. 2 is a perspective view illustrating a state where the ventricularassist device cannula with electrodes shown in FIG. 1 is mounted on ahuman body.

FIG. 3 is a partial cross-sectional view of a ventricular assist devicecannula with electrodes according to a second exemplary embodiment ofthe present invention.

FIG. 4 is an exploded side view of a ventricular assist device cannulawith electrodes according to a third exemplary embodiment of the presentinvention.

FIG. 5 is an exploded side view of a ventricular assist device cannulawith electrodes according to a fourth exemplary embodiment of thepresent invention.

FIG. 6 is a schematic configuration diagram illustrating a state where aventricular assist device including the ventricular assist devicecannula with electrodes shown in FIG. 1 and a defibrillator are mountedon a human body.

FIG. 7 is a conceptual diagram of a ventricular assist device includinga defibrillator according to an exemplary embodiment of the presentinvention.

FIG. 8 is a block diagram of the ventricular assist device shown in FIG.7.

FIG. 9 is a flowchart illustrating operational steps of the ventricularassist device shown in FIG. 7.

FIG. 10 is a conceptual diagram of a ventricular assist device includingan impedance measuring device according to an exemplary embodiment ofthe present invention

FIGS. 11 to 13 are diagrams illustrating variations in blood flow inaorta, arterial pressure, ECG, and impedance values when a stroke volumeof the ventricular assist device is 0.5, 1.0, and 1.5 L/min.

FIG. 14 is an enlarged view of a part of FIG. 13.

FIG. 15 is a flowchart illustrating steps of measuring an open and closetiming of cardiac valves and a cardiac output through a variation in animpedance value.

FIG. 16 is a flowchart illustrating steps of controlling a ventricularassist device by using an open and close timing of cardiac valves and acardiac output measured value.

FIGS. 17 and 18 are diagrams illustrating a state where electrodes areinstalled in a ventricular assist device including an apparatus ofmeasuring impedance according to other exemplary embodiments of thepresent invention.

FIG. 19 is a conceptual view of a ventricular assist device including anartificial pacemaker according to an exemplary embodiment of the presentinvention.

FIG. 20 is a block diagram of the ventricular assist device shown inFIG. 19.

FIG. 21 is a flowchart illustrating operational steps of the ventricularassist device shown in FIG. 19.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of a ventricular assist devicecannula with electrodes according to the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a ventricular assist device cannula withelectrodes according to a first exemplary embodiment of the presentinvention and FIG. 2 is a perspective view illustrating a state wherethe ventricular assist device cannula with electrodes shown in FIG. 1 ismounted on a human body.

Referring to FIGS. 1 and 2, a ventricular assist device cannula withelectrodes according to a first exemplary embodiment of the presentinvention includes a connecting tube 10 and a conductive sheet 20attached to the surface of the connecting tube 10.

The connecting tube 10 means a hollow elongated pipe so that blood canflow. The connecting tube 10 acts to connect the ventricular assistdevice with ventricles 1 and arteries 2 and transfer the blood of theventricles 1 to the arteries 2. The connecting tube 10 may be made of aflexible material, but is more preferably made of an elastic materialallowing contraction and expansion in order to serve as an apico aroticconduit (AAC) reducing a load of the heart when being not used as theventricular assist device. In addition, the connecting tube 10 ispreferably made of biomacromolecules having excellent bloodcompatibility and durability, for example, polyurethane for medical useand the like.

The conductive sheet 20 is attached to the surface of the connectingtube 10 and connected with a defibrillator, an artificial pacemaker, andthe like through wires 30. The conductive sheet 20 is made of Ag/AgCl,platinum (Pt), gold (Au), or other electrode materials. The conductivesheet 20 is attached to a position contacting a cross-section of anincision, when the connecting tube 10 is inserted to the ventricles 1and the arteries 2 through the incision of a body tissue such as theventricles 1 and the arteries 2. Accordingly, an electric signaltransferred through the conductive sheet 20 may be directly transferredto muscle cells or conductive fibers (purkinje fibers) of the heart,such that there is a merit that an electric stimulus can be efficientlyapplied to the whole heart even through small electric energy.

FIG. 3 is a partial cross-sectional view of a ventricular assist devicecannula with electrodes according to a second exemplary embodiment ofthe present invention. Referring to FIG. 3, the ventricular assistdevice cannula with electrodes according to the second exemplaryembodiment of the present invention includes a connecting tube 10 and ahollow electrode 40. Since the connecting tube 10 is the same as that ofthe first exemplary embodiment, the description thereof is omitted andonly the hollow electrode 40 will be described.

The hollow electrode 40 with a cylindrical shape has a hollow space 41into which the internal connecting tube 10 can be inserted. A receivinggroove 42 which can receive the incision of the body tissue is formedaround the hollow electrode 40. When the hollow electrode 40 is insertedthrough the incision of the body tissue, the incision of the body tissueis fitted into the receiving groove 42. The connecting tube 10 isinserted inside the body tissue through the hollow space 41 of thehollow electrode 40. A conductive layer 43 made of an electrode materialsuch as Ag/AgCl, platinum (Pt), gold (Au), or the like is formed insidethe receiving groove 42 of the hollow electrode 40 and connected with adefibrillator, an artificial pacemaker, and the like through the wires30. Meanwhile, the overall hollow electrode may be made of the electrodematerial without forming a separate conductive layer 43.

FIG. 4 is an exploded side view of a ventricular assist device cannulawith electrodes according to a third exemplary embodiment of the presentinvention. Referring to FIG. 4, the ventricular assist device cannulawith electrodes according to the third exemplary embodiment of thepresent invention includes a connecting tube 11 and an electrode 50including a body part 51 and a fixing part 54.

The body part 51 includes a hollow space (not shown) in which blood canflow and a receiving groove 52 for receiving an incision of the bodytissue around the body part 51 like the second exemplary embodiment. InFIG. 4, through-holes 53 through which the blood passes are formed at aleft end of the body part 51 and the fixing part 54 extending from thebody part 51 is formed at a right end of the body part 51.

The fixing part 54 is inserted into the connecting tube 11 to serve toconnect the electrode 50 and the connecting tube 11 and includes aprotrusion 55 for preventing a connecting part from being easilyseparated.

FIG. 5 is an exploded side view of a ventricular assist device cannulawith electrodes according to a fourth exemplary embodiment of thepresent invention. Referring to FIG. 5, the ventricular assist devicecannula with electrodes according to the fourth exemplary embodiment ofthe present invention includes a connecting tube divided into a firstconnecting tube 12 and a second connecting tube 13, and an electrode 60including a body part 61 and fixing parts 64.

A hollow space (not shown) in which blood can flow is formed inside thebody part 61 and an outer surface of the body part 61 is closelycontacted to the incision of the body tissue.

The fixing parts 64 extend to a left side and a right side from the bodypart 61, respectively and include protrusions 65 for preventing thefixing parts 64 from being easily separated from the connecting tubes 12and 13.

One end of the first connecting tube 12 is connected to the left fixingpart 64 and the other end thereof is inserted inside the body tissue,and one end of the second connecting tube 13 is connected to the rightfixing part 64 and the other end thereof is connected to the ventricularassist device (not shown).

FIG. 6 is a schematic configuration diagram illustrating a state where aventricular assist device including the ventricular assist devicecannula with electrodes shown in FIG. 1 and a defibrillator are mountedon a human body.

Referring to FIG. 6, the ventricular assist device includes an inflowconnecting tube 10 a connected to a cardiac apex 1 of a left ventricle,an outflow connecting tube 10 b connected to aorta 2, and a blood pump 3connected with the inflow connecting tube 10 a and the outflowconnecting tube 10 b. A one-way valve (not shown) permitting only onedirection flow of blood is installed at the inflow connecting tube 10 aand the outflow connecting tube 10 b. A battery and a control device 4are installed outside the body and connected to the blood pump 3 througha wire 5 by passing through skin. Ejection of the blood is controlled bythe control device 4 and the battery supplies power to the controldevice 4 and an electric motor.

A defibrillator 6 is connected to electrodes 20 of the inflow connectingtube 10 a and the outflow connecting tube 10 b through the wire 30 andconnected with the control device 4 by a wire 7 passing through theskin. Since the electrodes 20 are attached to the inflow connecting tube10 a and the outflow connecting tube 10 b, there is no need to implant aseparate wire into a heart or arteries. Although not shown, anelectrocardiograph for checking whether ventricular fibrillation occursis connected with the control device 4.

Hereinafter, operations of the ventricular assist device and thedefibrillator will be described shown in FIG. 6. When the blood pump 3operates in accordance with a signal of the control device 4, the bloodflows from the left ventricle 1 to the blood pump 3 through the inflowconnecting tube 10 a. The blood flowing into the blood pump 3 issupplied to the aorta 2 through the outflow connecting tube 10 b. Inthis case, the electrocardiograph (not shown) checks a state of theheart continuously to transfer the signal to the control device 4. Whenthe ventricular fibrillation is checked by the electrocardiograph, thecontrol device 4 stops operation of the blood pump 3 and operates thedefibrillator 6. The defibrillator 6 directly applies the electricstimulus to muscles of the ventricle 1 and the blood 2 through theelectrodes 20 installed at the inflow connecting tube 10 a and theoutflow connecting tube 10 b. If it is checked that a heart beat isrestored in a normal state by the electric stimulus, the control device4 operates the blood pump 3 again.

FIG. 7 is a conceptual diagram of a ventricular assist device includinga defibrillator according to an exemplary embodiment of the presentinvention and FIG. 8 is a block diagram of the ventricular assist deviceshown in FIG. 7.

Referring to FIGS. 7 and 8, like a general ventricular assist device, aventricular assist device including a defibrillator according to anexemplary embodiment of the present invention includes inflow conduits10 a and 20 into which the blood in a ventricle 1 flows while beingconnected to the ventricle 1, a blood pump 3 connected to the inflowconduits 10 a and 20 and pumping the blood, and outflow conduits 10 band 20 connecting the blood pump 3 and arteries 2 to transfer the bloodejected from the blood pump 3 to the arteries 2. The inflow conduits andthe outflow conduits are hollow elongated pipes so that the blood canflow. The inflow conduits and the outflow conduits may be theventricular assist device cannula shown in FIGS. 1 to 6.

The blood pump 3 may be classified into a pneumatic type and an electrictype. The electric type is subdivided into an electrohydraulic type andan electromechanical type. The blood pump 3 stores the blood flowingfrom the inflow connecting tube 10 a and includes a blood bag flowingout to the outflow connecting tube 10 b, air allowing the blood to flowby expanding and compressing the blood bag, and an electric device.Since the blood pump 3 uses a known device, the detailed descriptionthereof is omitted.

Referring to FIGS. 7 and 8, the ventricular assist device including thedefibrillator according to the exemplary embodiment of the presentinvention further includes a detecting device 8 detecting abnormality ornormality in the heart beat, a defibrillator 6 applying a defibrillationpulse to the electrodes 20 of the conduits to apply the electricstimulus to the heart, and a control device 4 controlling the blood pump3 and the defibrillator 6 by receiving the signal from the detectingdevice 8.

The detecting device 8 includes an electrocardiograph 8. Theelectrocardiogram records active current according to contraction of theheart in a curve line and is abbreviated to ECG or EKG. Since excitementof the heart muscle is generated from venous sinus to proceed in atriumand ventricle directions, when the excitement is induced to theelectrocardiograph in any two points, the active current of the heart isdrawn as a graph. As described above, the electrocardiogram is acquired.The abnormality or normality in the heart may be checked through theelectrocardiogram. The detecting device 8 transmits measured data to thecontrol device 4.

The defibrillator 6 includes a high voltage generating part for applyingan electric impact and a high voltage switching part for dischargingcurrent generated from the high voltage generating part to a human body.The defibrillator 6 is implanted in a chest with being not seen at theoutside or implanted together with being included in the control device4. Since the defibrillator 6 uses a known device, the detaileddescription thereof is omitted.

The control device 4 includes a microcontroller which processes a signalmeasured through the detecting device 8 and determines the electricimpact or not and an electric impact amount. The microcontrollercontrols the high voltage generating part of the defibrillator 6. Inaddition, the microcontroller controls the blood pump 3. Further, thecontrol device 4 further includes an external alarm device (not shown)sounding the alarm when the ventricular fibrillation is checked.

FIG. 9 is a flowchart illustrating operational steps of the ventricularassist device shown in FIG. 7.

Referring to FIG. 9, operational steps of a ventricular assist deviceincluding a defibrillator according to an exemplary embodiment of thepresent invention start from measuring a cardiac state through adetecting device. If the measured signal is processed in a controldevice and there is no abnormality, a driving signal is transferred to ablood pump to drive the blood pump. If ventricular fibrillation isdetected, an external alarm is sounded and an electric impact amount isdetermined to set defibrillation energy. When preparation for adefibrillation pulse is completed by charging the defibrillation energy,damage of the blood pump due to the defibrillation pulse is prevented byblocking a power supply for operation of the blood pump and entering aprotection mode blocking input and output signals. If the ventricularfibrillation is removed by checking the defibrillation, the protectionmode is released and the blood pump is operated again and if thedefibrillation is failed, an inability alarm of the defibrillation issounded.

Meanwhile, the detecting device 8 is described as a generally usedelectrocardiograph 8, but the detecting device 8 may use a pressuresensor installed at an inlet of the inflow conduit 10 a. If theventricular fibrillation occurs, each portion of the ventricle isdisorderedly and irregularly contracted and flowability of blood flowingin through the inlet of the inflow conduit 10 a becomes irregular. As aresult, when the flowability is measured through the pressure sensor,the ventricular fibrillation or not may be checked. In addition, if acardiac arrest occurs, the blood flowing into the inflow conduit 10 adecreases and a pressure drops, such that the cardiac arrest or not maybe checked. Further, as a method of measuring impedance between theelectrodes of the inflow conduit and the outflow conduit, a detectingdevice measuring a cardiac abnormality such as the ventricularfibrillation, the cardiac arrest, and the like may be used. Sinceimpedance between the electrodes 20 of the inflow conduit and theoutflow conduit is changed according to a blood flow between theventricle and the aorta, the cardiac abnormality or normality may bedetected by measuring the impedance.

FIG. 10 is a conceptual diagram of a ventricular assist device includingan impedance measuring device according to an exemplary embodiment ofthe present invention.

Referring to FIG. 10, like a general ventricular assist device, aventricular assist device including an impedance measuring deviceaccording to an exemplary embodiment of the present invention includesinflow conduits 10 a and 20 into which the blood in a ventricle 1 flowswhile being connected to the ventricle 1, a blood pump 3 connected tothe inflow conduits 10 a and 20 and pumping the blood, and outflowconduits 10 b and 20 connecting the blood pump 3 and arteries 2 totransfer the blood ejected from the blood pump 3 to the arteries 2. Theinflow conduits and the outflow conduits are hollow elongated pipes sothat the blood can flow. The inflow conduits and the outflow conduitsmay be the ventricular assist device cannula shown in FIGS. 1 to 6.

The blood pump 3 may be classified into a pneumatic type and an electrictype. The electric type is subdivided into an electrohydraulic type andan electromechanical type. The blood pump 3 stores the blood flowingfrom the inflow connecting tube 10 a and includes a blood bag flowingout to the outflow connecting tube 10 b, air allowing the blood to flowby expanding and compressing the blood bag, and an electric device.Since the blood pump 3 uses a known device, the detailed descriptionthereof is omitted.

Referring to FIG. 10, the ventricular assist device including animpedance measuring device according to the exemplary embodiment of thepresent invention further includes an impedance measuring device 6 and acontrol device 4 controlling the blood pump 3 by receiving a signal fromthe impedance measuring device 6.

The impedance measuring device 6 is connected to electrodes 20 through awire 30. The impedance measuring device 6 includes a power supply devicecapable of applying high-frequency AC current. The high-frequency ACcurrent is generated from the power supply device and the AC current isapplied to the heart through the electrodes. When high-frequency current(30 kHz, 0.2 mA) having a sine waveform was applied between the heartand the blood vessel of a patient using the ventricular assist device,it was verified that the current has no influence on a nerve, muscle, orheart tissue. As the high-frequency current generated from the powersupply device passes the heart and the blood vessel through theelectrodes, high-frequency voltage is generated in proportion tomagnitudes of impedances of the heart and the blood vessel. Theimpedance measuring device measures variation in an impedance value bymeasuring and recording the high-frequency voltage generated by thechange of the impedance due to the heart beat.

FIGS. 11 to 13 are diagrams illustrating variations in blood flow inaorta, arterial pressure, ECG, and impedance values when a stroke volumeof the ventricular assist device is 0.5, 1.0, and 1.5 L/min. In ananimal test using a pig of 40 Kg, the variations were measured byinserting an inflow conduit and an outflow conduit where electrodes areattached to a depth of a left ventricle and aorta. The variation in theblood flow in aorta was measured by using an ultrasonic flowmeterinstalled at an aortic arch.

As shown in FIGS. 11 to 13, the impedance value was changed according toopen and close of cardiac valves, blood flow in ventricles, and bloodflow in aorta. The open and close of the cardiac valves was verifiedthrough the aortic pressure. When the heart was contracted and theaortic valves opened, the impedance had a minimum value and when thearterial pressure was most low with the cardiac valves opened, theimpedance had a maximum value. The impedance was increased and decreasedwhen the cardiac valves opened and closed and particularly, inflectionpoints were generated during the change of the impedance by the motionof the valves.

FIG. 14 is an enlarged view of a part of FIG. 13. In Period 1, impedanceincreases due to ventricular systole and in Period 2, the impedancedecreases due to expansion of artery. In Period 3, a slope in which theimpedance decreases due to the close of an aortic valve is changed. InPeriod 4, the impedance decreases due to expansion of the ventricle andin Period 5, the expansion of the ventricle stops and the blood vesselis contracted, such that the impedance increases after passing theminimum value. In Period 6, the impedance decreases due to atrialsystole, an additional expansion of the ventricle, and a temporary openof the aortic valve and in Period 7, the aortic valve is closed and theaorta is contracted, such that the impedance increases. In Period 8, theimpedance decreases due to the open of the aortic valve. As describedabove, the impedance value is changed according to an open and closetiming of the cardiac valves and contraction and expansion of the heart.Accordingly, the open and close timing of the cardiac valves and thecardiac output may be measured through the variation in the impedancevalue. FIG. 15 is a flowchart illustrating steps of measuring an openand close timing of cardiac valves and a cardiac output through avariation in an impedance value.

Referring to FIG. 15, an example of calculating the open and closetiming of cardiac valves and the cardiac output by measuring theimpedance will be described.

First, a maximum value I_(max) of impedance I and a time T_(max) aremeasured. The maximum value I_(max) of impedance I is measured when theventricle is maximally contracted. Next, inflection points and a time T₁are measured by differentiating the impedance I. The inflection pointbetween the maximum value I_(max) and a minimum value I_(min) ofimpedance I is generated by the close of the cardiac valves. Next, theminimum value I_(min) and a time T_(min) of the impedance are measured.The minimum value I_(min) of impedance I is measured when the ventricleis maximally expanded. Next, inflection points and a time T₂ aremeasured again by differentiating the impedance I. The inflection pointsafter the minimum value I_(min) are generated by the open of the cardiacvalves.

The cardiac output CO may be calculated by multiplying an appropriateproportional constant C and a value obtained by multiplying a differencebetween the maximum value I_(max) and minimum value I_(min) of theimpedance I by heart rate HR. The heart rate HR may be measured by aninterval between the open time T₂ and the close time T₁ of the cardiacvalves or an interval between a time T_(max) reaching the maximum valueof the impedance and a time T_(min) reaching the minimum value of theimpedance.

The control device 4 processes the signal measured by the impedancemeasuring device 6 through the microcontroller and controls the bloodpump 3.

FIG. 16 is a flowchart illustrating steps of controlling a ventricularassist device by using an open and close timing of cardiac valves and acardiac output measured value.

As shown in FIG. 16, the ventricular assist device may be controlled bycomparing a cardiac output and a value obtained by multiplying acirculation amount of the entire blood flow by an input constant P1 andconsidering the open and close timing of cardiac valves. That is, thecontrol device reduces the blood flow speed of the ventricular assistdevice when the circulation of the entire blood flow is reduced, suchthat the blood vessel is prevented from being contracted or damaged dueto an excessive inflow of the blood flow. In addition, the controldevice may optimally control the blood pump 3 by a method of minimizinga load applied to the heart of the patient by preventing the bloodejection of the ventricular assist device in the heart ejection.

FIGS. 17 and 18 are diagrams illustrating a state where electrodes areinstalled according to other exemplary embodiments of the presentinvention.

As shown in FIGS. 17 and 18, instead of installing electrodes at theoutflow conduit, an electrode 22 may be attached to the outside of thebody around arteries and an implantable electrode 22 may be installedaround the arteries inside the body.

FIG. 19 is a conceptual view of a ventricular assist device including anartificial pacemaker according to an exemplary embodiment of the presentinvention and FIG. 20 is a block diagram of the ventricular assistdevice shown in FIG. 19.

Referring to FIGS. 19 and 20, like a general ventricular assist device,a ventricular assist device including an artificial pacemaker accordingto an exemplary embodiment of the present invention includes inflowconduits 10 a and 20 into which the blood in a ventricle 1 flows whilebeing connected to the ventricle 1, a blood pump 3 connected to theinflow conduits 10 a and 20 and pumping the blood, and outflow conduits10 b and 20 connecting the blood pump 3 and arteries 2 to transfer theblood ejected from the blood pump 3 to the arteries 2. The inflowconduits and the outflow conduits are hollow elongated pipes so that theblood can flow. The inflow conduits and the outflow conduits may be theventricular assist device cannula shown in FIGS. 1 to 6.

The blood pump 3 may be classified into a pneumatic type and an electrictype. The electric type is subdivided into an electrohydraulic type andan electromechanical type. The blood pump 3 stores the blood flowingfrom the inflow connecting tube 10 a and includes a blood bag flowingout to the outflow connecting tube 10 b, air allowing the blood to flowby expanding and compressing the blood bag, and an electric device.Since the blood pump 3 uses a known device, the detailed descriptionthereof is omitted.

Referring to FIGS. 19 and 20, the ventricular assist device including anartificial pacemaker according to the exemplary embodiment of thepresent invention further includes detecting devices 8 and 9 detectingcardiac signals such as heart rate, a QRS generating time, a cardiacoutput, an open and close timing of cardiac valves, and the like, anartificial pacemaker 6 applying an electric stimulus to the heartthrough the electrode 20 of the conduit, and a control device 4controlling the blood pump 3 and the artificial pacemaker 6 by receivingthe signal from the detecting devices 8 and 9.

The detecting device includes an electrocardiograph 8. Theelectrocardiogram records active current according to contraction of theheart in a curve line and is abbreviated to ECG or EKG. Since excitementof the heart muscle is generated from a venous sinus to proceed inatrium and ventricle directions, when the excitement is induced to theelectrocardiograph in two arbitrary points, the active current of theheart is drawn as a graph. As described above, the electrocardiogram isacquired. A contracted state or a relaxed state of the heart may bedetermined through the electrocardiogram.

Further, the detecting device further includes an impedance measuringdevice 9 measuring the impedance between the electrodes 20 of the inflowconduit and the outflow conduit. As the high-frequency current generatedfrom the power supply device of the impedance measuring device 9 passesthe heart and the blood vessel through the electrodes, high-frequencyvoltage is generated in proportion to magnitudes of impedances of theheart and the blood vessel. The impedance measuring device 9 measuresvariation in an impedance value by measuring and recording thehigh-frequency voltage generated by the change of the impedance due tothe heart beat. The impedance value is changed according to open andclose of cardiac valves, blood flow in ventricles, and blood flow inaorta, such that an open and close timing of the cardiac valves andvariation in blood flow may be measured by using the variation in theimpedance value.

The artificial pacemaker 6 is implanted in the upper side of a chestwith being not seen at the outside or implanted together with beingincluded in the control device 4. The artificial pacemaker 6 includes abattery power management circuit for transferring the stimulus to theheart, a voltage/current reference oscillator, a high voltagemultiplier, a high voltage output pulse generator, and the like. Inaddition, the power can be supplied through the ventricular assistdevice during the charging or in emergency. Since the artificialpacemaker 6 uses a known device, the detailed description thereof isomitted.

The control device 4 includes an integrated circuit which processes thesignals measured through the detecting devices 8 and 9, monitors thevariations in a heart beat speed, an open and close timing of thecardiac valves, and the variation in the blood flow, supplies thestimulus by controlling the artificial pacemaker 6 if necessary, and cancontrol the blood flow ejected through the ventricular assist device bycontrolling the blood pump 3.

FIG. 21 is a flowchart illustrating operational steps of the ventricularassist device shown in FIG. 19.

Referring to FIG. 21, operational steps of a ventricular assist deviceincluding an artificial pacemaker according to an exemplary embodimentof the present invention start from measuring a cardiac state through adetecting device. Whether the heart of patient is in the contractedstate or the relaxed state is determined by analyzing a cardiac signaland the blood pump operates after delay times D1 and D2 inputtedaccording to the cardiac state elapse. In this case, an output by theblood pump is optimized by using the cardiac output calculated bymeasuring the impedance of the heart. In the case where the heart rateis lower than pulsation rate of the blood pump, the heart rate iscontrolled so as to be equal to the pulsation rate of the blood pump byapplying the stimulus to the heart through the artificial pacemaker. Inthe case where the heart rate is one to two times higher than pulsationrate of the blood pump, the heart rate is controlled so as to be twotimes higher than the pulsation rate of the blood pump by applying thestimulus to the heart through the artificial pacemaker. That is, whenthe patient's heart pulsates twice, the blood pump pulsates once. In thecase where the heart rate is two to three times higher than pulsationrate of the blood pump, the heart rate is controlled so as to be threetimes higher than the pulsation rate of the blood pump by applying thestimulus to the heart through the artificial pacemaker. That is, whenthe patient's heart pulsates three times, the blood pump pulsates once.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A ventricular assist device cannula withelectrodes, comprising: a connecting tube connecting an incision of abody tissue and a ventricular assist device so that blood can flow; andelectrodes connected with the connecting tube and contacting theincision of the body tissue to transfer an electric signal to the bodytissue.
 2. The ventricular assist device cannula with electrodes ofclaim 1, wherein: the electrode is a conductive sheet attached to thesurface of the connecting tube.
 3. The ventricular assist device cannulawith electrodes of claim 1, wherein: the electrode is a hollow electrodewhich has a hollow space into which the connecting tube is inserted atthe inside thereof and is closely contacted to the incision of the bodytissue at the outside thereof.
 4. The ventricular assist device cannulawith electrodes of claim 3, wherein: a receiving groove receiving theincision of the body tissue is formed at an outer circumference of thehollow electrode.
 5. The ventricular assist device cannula withelectrodes of claim 1, wherein: the electrode is a connector electrodewhich has hollow space where the blood can flow at the inside thereofand includes a body part contacted to the incision of the body tissueand inserted into the body tissue and a fixing part extending from thebody part and inserted and fixed to the connecting tube at the outsidethereof.
 6. The ventricular assist device cannula with electrodes ofclaim 5, wherein: a receiving groove receiving the incision of the bodytissue is formed at an outer circumference of the body part.
 7. Theventricular assist device cannula with electrodes of claim 1, wherein:the electrode has hollow space where the blood can flow at the insidethereof and includes a body part contacted to the incision of the bodytissue and fixing parts extending from the body part to the upstream andthe downstream, respectively, at the outside thereof, and the connectingtube includes a first connecting tube having one end connected to thefixing part and the other end inserted into the body tissue and a secondconnecting tube having one end connected to the fixing part and theother end connected to the ventricular assist device.
 8. The ventricularassist device cannula with electrodes of claim 7, wherein: a receivinggroove receiving the incision of the body tissue is formed at an outercircumference of the body part.